Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 10/11/2022 - 18:04
I wonder whether someone here managed to observe the afterglow of GRB 221009A, which apparently had a really bright optical signal.
https://twitter.com/swift_phil/status/1579485506475544576
CS
HB
I didn't observe it, but I have seen that it reached 16th magnitude in the early afterglow. Swift's Burst Alert Telescope triggered not on the prompt emission from the burst, but on the early afterglow. It may still be possible to do tonight for some of the better equipped AAVSO members.
Definitely worth observing! It's pretty much in the galactic plane...so if the afterglow is bright....could this be.... a GRB in our own galaxy? Exciting!
CS
HB
It's been established to be at redshift of 0.1505, so it's really nearby relative to the typical gamma-ray burst, but it's not in our own Galaxy. A GRB in our own Galaxy would probably be observable in the daytime with the unaided eye, unless it were really behind a whole lot of dust.
Ah I see, thx! Still, a very interesting object!
CS
HBE
P.S.: I guess some special types of galactic GRBs could still be non-obvious in the optical, e.g. there were GRBs associated with the first galactic Fast-Radio-Burst source if I remember correctly.
Yes, that's right. The giant outbursts from magnetars would give flashes of gamma-rays and not be bright optical sources. In the early days of GRB studies, people realized that a small fraction of the GRBs had spectra dominated by lower energy gamma-rays, and that these objects repeated, and that they were all in the Galactic Plane or in the Magellanic Clouds. These got split off, so that most people working on gamma-ray bursts no longer count those as gamma-ray bursts.
And by now, with current knowledge and gamma-ray detectors, even if there were a new magnetar having its first big outburst, we'd probably recognize that it was one of those pretty quickly, unless we got one that behaved differently from the others.
Looks like it could still be detectable in R, perhaps I bands with bigger scopes.
Note that it's "Full Moon Happy Hour" at iTelescope, so everyone with an iTelescope account can give it a try with a one hour live imagining session.
E.g. observations from the New Mexico site in the first half of the night should work very well, air mass wise.
Cheers
HB.
Hello to all!
I observed the optical afterglow of the extremely bright GRB 221009A (Swift J1913.1+1946) using remote 0.61-m f/6.5 telescopes (with Cousins Ic photometric filters): of Burke-Gaffney Observatory (in Halifax, Canada) and itelescope.net T24 in Sierra Remote Observatory (Auberry, California, USA) - from October 10 to October 13, 2022.
Due to the fact that telescopes and filters are the same, I made a comparative animation of the fading of the optical afterglow of this unique gamma-ray burst.
I measured the brightness in the first image: 15.65 Ic https://gcn.gsfc.nasa.gov/gcn3/32664.gcn3 , in the second: 17.1 Ic https://gcn.gsfc.nasa.gov/gcn3/32679.gcn3
With best regards, Filipp.
Nice catch, thanks for sharing the annimation.
Have you thought about sharing your inmages with KilonovaCatcher? http://kilonovacatcher.in2p3.fr
I'm sure they could use extra data, and together with other contributors there should be a nice light curve from amateur observations.
Cheers
HBE
Thank you!
I tried adding the images to KilonovaCatcher, but I get an error: "This Event is over OR There is no tiles associated to this user's telescopes and this event !"
I wrote asking to fix it.
With best wishes, Filipp.
Pan-STARRS guys wrote:
"We observed an initial fade of approximately 0.9 mags per day in i, z and y, slowing to about 0.4 mags per day in these filters over the last 2 days."
https://gcn.gsfc.nasa.gov/gcn/gcn3/32758.gcn3
I wonder what kind of object was this event?
I guess for now the leading explanation is that this is not different in principle from any other long GRB, just brighter than average, both intrinsically and because it was relatively close: a core collapse supernova of a rotating, heavy star that led to a gammy ray beam that happend to be pointing exactly our way. At a redshift of z~0.15, I guess this would mean that the afterglow was the last thing we amateurs could see from this event, but time will tell.
P.S.: If some here now think: 'too bad, I could have observed this "once-per-lifetime event" (as it is now called in some media) but I didn't learn about it in time' : Maybe you should consider using the Astro-Colibri web- and phone-app that can alert you about GRBs. There is usually ca one alert per day on average, but if you want to focus on alerts that are localized on the sky well enough to check tfor an afterglow with a single pointing, you could focus on SWIFT alerts which are happening more like once per week.
Web app: https://astro-colibri.com/#/
Phone App: search for "Astro-Colibri" in the Google or Apple app-stores.
CS
HB
We should include Filipp's animation of the GRB on the HEN webpage. It's an excellent example of imaging GRBs. I've privately contacted him with this idea.
Dave
Yes, of course, I allow to publish this my animation on the AAVSO website so that people can see how the brightness of the optical afterglow of the gamma-ray burst decreases.
I saw that AAVSO VLF Observer Ján Karlovský detected the GRB 221009A SID event and published https://spaceweathergallery.com/indiv_upload.php?upload_id=189363 the result.
Here is a GCN circular that communicates several amateur observations of GRB 221009A, as coordinated by the KilonovaCatcher/GRANDMA project.
https://gcn.gsfc.nasa.gov/gcn3/32934.gcn3
GCN Circulars are free-text messages written by humans and intended for human readers. There is another type of GCN messages, GCN notices, which are (mostly) machine generated and intended to be digested by "machines" (well, software). It's nice to see that amateurs, thru collaboration with professional astronomers, can use this platform to communicate their contributions, isn't it?
Clear Skies
HB